The present invention relates to a tool for establishing interproximal contact between a plastic filling in a bored out tooth cavity and a contact surface on an adjacent tooth, the tool having a head with a first convex surface facing forward relative to a handle, the head being configured to fit into the bored out cavity in the tooth, such that the head extends from the handle on the tool and downwards into the cavity, and where the head includes pins that are separated by interstice.
U.S. Pat. No. 5,318,446 describes such a tool. The tool is made from transparent plastic. The tool has a head that includes two pins. On one side, the pins have convex surfaces and on the other side, the pins have plane surfaces. The convex surface is designed to press plastic into a plastic filling and a matrix band that is arranged around the tooth for outward contact with the contact surface on the adjacent tooth. Hereafter, the plastic is hardened by means of light from a light source through the transparent tool. After this, the tool is removed, and the holes in the plastic filling caused by the pins are refilled with plastic filling material and are hardened with the light source.
This tool does, however, have some disadvantages. The tool has two separate pins. An interstice is established between the pins. The interstice is exactly opposite the most projecting point of the adjacent tooth surface when the tool is arranged in the cavity in the tooth. The matrix band that runs between the tool and the adjacent tooth is made from a very thin metal foil. Thus, there will be the risk that the matrix band at the position of the interstice in the tool will bend inwards against the interproximal cavity in the tooth away from the adjacent tooth surface and create a distance between the matrix band and the adjacent tooth surface. This implies that the interproximal contact between the adjacent teeth is not obtained at all, and the plastic filling's contact surface is thereby lost at a substantial and critical place. Moreover, the pins on the tool take up a lot of space in the bored out interproximal cavity, which makes it difficult to see the work during the plastic filling. This also means that the holes after the pins, when the first plastic filling is performed, are very large, which implies that a large part of the plastic filling against the adjacent tooth surface is performed without the matrix band being pressed outwards at the same time. Therefore, the matrix band can also risk not having interproximal contact to the adjoining tooth during the following plastic filling and final hardening. Moreover, the contact surface of the tool is only convex in one plane, which gives an insufficient contact against the adjoining tooth. Moreover, the tool is elastic, which make the application in the working process unstable.
U.S. Pat. No. 4,726,770 describes a transparent glass wedge for placement in a filling in a cavity in a tooth. The glass wedge has a convex surface facing forward with a so-called “knuckle”, and by means of a handle and plastic in the plastic filling, the knuckle presses the matrix band and the plastic outwards against the contact surface on the adjacent tooth. Hereafter, the plastic is hardened through the transparent glass wedge, and after that, the glass wedge continues to be part of the filling. The knuckle on the wedge is made in such a way that when the tip of the wedge rests at the bottom of the cavity in the tooth, then the knuckle will be directly opposite the point on the adjacent tooth where the interproximal contact must be established. Until the filling is hardened, the wedge is maintained pressed outwards against the matrix band by means of a handle. When the filling is hardened, the glass wedge remains in the filling, and thus makes up part of the filling in the cavity.
This means for filling does not make up a tool as such, but makes up an actual part of the filling, which remains inside the filling. However, the wedge is supplied with a so-called “kuckle”, which is to ensure that the interproximal contact between the adjacent teeth remains at exactly one single point. However, the wedge only obtains the desired effect, if the knuckle is made exactly opposite the corresponding convexity on the side of the adjacent tooth. If the knuckle is made too high or too low in relation to this, then the desired effect will not be obtained. This means that each wedge must be shaped individually in consideration of the dental patient in question and in consideration of the individual bored out cavities' shape and size, particularly upwards and downwards. It is moreover difficult to maintain the wedge with adequately large pressure outwards against the matrix band with adequately large pressure and out against the contact surface on the adjacent tooth. Moreover, there is a disadvantage that part of the filling is made of glass, while another part of the filling is made of another material. Thus, there will be a large risk that the glass wedge slides out of the filling, if the two materials, respectively glass and for example plastic react differently under given influences such as hot and cold drinks, mechanical strain, when chewing is performed etc.